The goal of this research is to determine the extent to which social interaction between male and female rhesus monkeys coordinates the reproductive states of the animals. Free ranging rhesus monkeys on island colonies in Puerto Rico breed with a seasonal rhythm and we have found that males captured from the colony during the non-mating portion of the year can be returned to mating condition by exposure to females artificially brought into estrus. This finding has now been extended to the free ranging social groups by showing that two females implanted with estradiol pellets during the non-mating season were capable of inducing a wave of sexual activities among adult males in the group. In the proposed study an attempt will be made to induce sexual activity in female monkeys during the non-mating period by exposure to sexually active males. The sexual activity of the female will be monitored by measures of behavior and gonadal hormones.